1. Field of the Invention
The present invention relates to an elevator control device.
2. Description of Related Art
A related elevator control device adopts such a system that an inverter device is used for driving an alternating-current (AC) motor (hereinafter, also simply referred to as a motor). Herein, the inverter device subjects a switching element, such as a power transistor or an IGBT (Insulated Gate Bipolar Transistor), to PWM (Pulse Width Modulation) control. It is assumed herein that an inverter device is selected from a viewpoint of generating a torque required in normal operation of an elevator. In such a case, the selected inverter device becomes short of capacitance in overloaded test operation to be carried out at the time of completion or performance evaluation of the elevator. When being selected in consideration of such a test, an inverter device disadvantageously increases in cost and size.
JP 06-009165 A discloses a technique for making a carrier frequency variable in accordance with an operating speed of an inverter device. Moreover, JP 2005-162376 A discloses a technique for switching a coil of a motor to be driven and decreasing a carrier frequency. A decreased carrier frequency of an inverter device allows suppression of a loss caused to a switching element. Therefore, it becomes possible to produce higher torque and larger electric current in an inverter device with invariable capacitance.